2. Part I: Overview
Core concepts presented:
– What is network monitoring
– What is network management
– Getting started
– Why network management
– Attack detection
– Consolidating the data
– The big picture
3. What is network monitoring?
Anyone have some ideas?
Monitoring an active communications network in order to
diagnose problems and gather statistics for
administration and fine tuning.
The term network monitoring describes the use of a
system that constantly monitors a computer network for
slow or failing components and that notifies the network
administrator in case of outages via email, pager or
other alarms. It is a subset of the functions involved in
network management.
4. What is network management?
Refers to the broad subject of managing computer
networks. There exists a wide variety of software and
hardware products that help network system
administrators manage a network. Network
management covers a wide area, including:
- Security: Ensuring that the network is protected from
unauthorized users.
- Performance: Eliminating bottlenecks in the network.
- Reliability: Making sure the network is available to users and
responding to hardware and software malfunctions.
5. System & Service monitoring
Reachability, availability
Resource measurement/monitoring
Capacity planning, availability
Performance monitoring (RTT, throughput)
Statistics & Accounting/Metering
Fault Management (Intrusion Detection)
Fault detection, troubleshooting, and tracking
Ticketing systems, help desk
Change management and configuration
monitoring
What is network management?
6. Make sure that the network is up and running.
Thus, we need to monitor it:
Deliver projected SLAs (Service Level
Agreements)
Depends on policy
What does your management expect?
What do your users expect?
What do your customers expect?
What does the rest of the Internet expect?
Is 24x7 good enough?
There's no such thing as 100% uptime (as we’ll see)
Getting started
7. What does it take to deliver 99.9 % uptime?
30.5 x 24 = 762 hours a month
(762 – (762 x .999)) x 60 = 45 minutes
only 45 minutes of downtime a month!
Need to shutdown 1 hour / week?
(762 - 4) / 762 x 100 = 99.4 %
Remember to take planned maintenance into
account in your calculations, and inform your
users/customers if they are included/excluded
in the SLA
How is availability measured?
In the core? End-to-end? From the Internet?
Getting started: “Uptime”
8. Getting started: Baselining
What is normal for your network?
If you’ve never measured or monitored your
network you need to know things like:
– Load on links
– Jitter between endpoints
– Percent usage of resources
– Amount of “noise”:
• Network scans
• Dropped data
• Reported errors or failures
9. Know when to upgrade
Is your bandwidth usage too high?
Where is your traffic going?
Do you need to get a faster line, or more providers?
Is the equipment too old?
Keep an audit trace of changes
Record all changes
Makes it easier to find cause of problems due to
upgrades and configuration changes
Keep a history of your network operations
– Using a ticket system let you keep a history of events.
– Allows you to defend yourself and verify what happened
Why network management?
10. Accounting
– Track usage of resources
– Bill customers according to usage
Know when you have problems
Stay ahead of your users! Makes you look good.
Monitoring software can generate tickets and auto-
matically notify staff of issues.
Trends
– All of this information can be used to view trends
across your network.
– This is part of baselining, capacity planning and
attack detection.
Why network management?
11. • Trends and automation allow you to know
when you are under attack.
• The tools in use can help you to mitigate
attacks:
– Flows across network interfaces
– Load on specific servers and/or services
– Multiple service failures
Attack Detection
12. Consolidating the data
The Network Operations Center (NOC)
“Where it all happens”
Coordination of tasks
Status of network and services
Fielding of network-related incidents and
complaints
Where the tools reside (”NOC server”)
Documentation including:
Network diagrams
database/flat file of each port on each switch
Network description
Much more as you'll see a bit later.
13. - Monitoring
- Data collection
- Accounting
- Capacity planning
- Availability (SLAs)
- Trends
- Detect problems
- Change control &
monitoring
- Improvements
- Upgrades
- Fix problems
- User complaints
- Requests
- NOC Tools
- Ticket system
Ticket
Ticket
Ticket
Ticket
Ticket
Notifications
The big picture
16. Part II: Details
Some details on the core concepts:
• Network documentation
• Diagnostic tools
• Monitoring tools
• Performance tools
• Active and passive tools
• SNMP
• Ticket systems
• Configuration and change management
17. Maybe you’ve asked, “How do you keep track
of it all?”...
Document,
document,
document…
Documentation
18. Basics, such as documenting your switches...
– What is each port connected to?
– Can be simple text file with one line for every port in a
switch:
• health-switch1, port 1, Room 29 – Director’s office
• health-switch1, port 2, Room 43 – Receptionist
• health-switch1, port 3, Room 100 – Classroom
• health-switch1, port 4, Room 105 – Professors Office
• …..
• health-switch1, port 25, uplink to health-backbone
– This information might be available to your network staff,
help desk staff, via a wiki, software interface, etc.
– Remember to label your ports!
Documentation
20. Network Documentation
More automation might be needed. An
automated network documentation system
is something to consider.
– You can write local scripts to do this.
– You can consider some automated
documentation systems.
– You’ll probably end up doing both.
21. Automated Systems
There are quite a few automated network
documentation systems. Each tends to do
something different:
– IPplan:
http://iptrack.sourceforge.net/
– Netdisco:
http://netdisco.org/
– Netdot:
https://netdot.uoregon.edu/
22. IPplan:
From the IPplan web page:
“IPplan is a free (GPL), web based, multilingual, TCP IP address management
(IPAM) software and tracking tool written in php 4, simplifying the
administration of your IP address space. IPplan goes beyond TCPIP address
management including DNS administration, configuration file management,
circuit management (customizable via templates) and storing of hardware
information (customizable via templates).”
Lots of screenshots:
http://iptrack.sourceforge.net/doku.php?id=screenshots
23. Netdisco:
• Project launched 2003. Version 1.0
released October 2009.
• Some popular uses of Netdisco:
– Locate a machine on the network by MAC or IP and
show the switch port it lives at.
– Turn Off a switch port while leaving an audit trail.
Admins log why a port was shut down.
– Inventory your network hardware by model, vendor,
switch-card, firmware and operating system.
– Report on IP address and switch port usage: historical
and current.
– Pretty pictures of your network.
24. Netdot:
Includes functionality of IPplan and Netdisco
and more. Core functionality includes:
– Device discovery via SNMP
– Layer2 topology discovery and graphs, using:
• CDP/LLDP
• Spanning Tree Protocol
• Switch forwarding tables
• Router point-to-point subnets
– IPv4 and IPv6 address space management (IPAM)
• Address space visualization
• DNS/DHCP config management
• IP and MAC address tracking
Continued
25. Netdot:
Functionality continued:
– Cable plant (sites, fiber, copper, closets, circuits...)
– Contacts (departments, providers, vendors, etc.)
– Export scripts for various tools
(Nagios, Sysmon, RANCID, Cacti, etc)
• I.E., how we could automate node creation in Cacti!
– Multi-level user access: Admin, Operator, User
– It draws pretty pictures of your network
28. Three kinds of tools
1. Diagnostic tools – used to test connectivity,
ascertain that a location is reachable, or a
device is up – usually active tools
2. Monitoring tools – tools running in the
background (”daemons” or services), which
collect events, but can also initiate their own
probes (using diagnostic tools), and recording
the output, in a scheduled fashion.
Network monitoring systems & tools
29. 3. Performance Tools
Key is to look at each router interface (probably
don’t need to look at switch ports).
Two common tools:
- Netflow/NfSen: http://nfsen.sourceforge.net/
- MRTG: http://oss.oetiker.ch/mrtg/
MRTG = “Multi
Router Traffic
Grapher”
Network monitoring systems & tools
30. Active tools
Ping – test connectivity to a host
Traceroute – show path to a host
MTR – combination of ping + traceroute
SNMP collectors (polling)
Passive tools
log monitoring, SNMP trap receivers, NetFlow
Automated tools
SmokePing – record and graph latency to a set of hosts,
using ICMP (Ping) or other protocols
MRTG/RRD – record and graph bandwidth usage on a
switch port or network link, at regular intervals
Network monitoring systems & tools
31. Network & Service Monitoring tools
Nagios – server and service monitor
Can monitor pretty much anything
HTTP, SMTP, DNS, Disk space, CPU usage, ...
Easy to write new plugins (extensions)
Basic scripting skills are required to develop simple
monitoring jobs – Perl, Shell scripts, php, etc...
Many good Open Source tools
Zabbix, ZenOSS, Hyperic, OpenNMS ...
Use them to monitor reachability and
latency in your network
Parent-child dependency mechanisms are very useful!
Network monitoring systems & tools
32. Monitor your critical Network Services
DNS/Web/Email
Radius/LDAP/SQL
SSH to routers
How will you be notified?
Don't forget log collection!
Every network device (and UNIX and Windows servers
as well) can report system events using syslog
You MUST collect and monitor your logs!
Not doing so is one of the most common mistakes
when
doing network monitoring
Network monitoring systems & tools
33. SNMP – Simple Network Management
Protocol
Industry standard, hundreds of tools exist to exploit it
Present on any decent network equipment
Network throughput, errors, CPU load, temperature, ...
UNIX and Windows implement this as well
Disk space, running processes, ...
SSH and telnet
It is also possible to use scripting to automate
monitoring of hosts and services
Network management protocols
34. Net SNMP tool set
- http://net-snmp.sourceforge.net/
Very simple to build simple tools
One that builds snapshots of which IP is used by which
Ethernet address
Another that builds shapshots of which Ethernet
addresses exist on which port on which switch.
Query remote RAID array for state.
Query server, switches and routers for temperatures.
Etc…
SNMP tools
35. Traffic accounting and analysis
What is your network used for, and how much
Useful for Quality of Service, detecting abuses,
and billing (metering)
Dedicated protocol: NetFlow
Identify traffic ”flows”: protocol, source,
destination, bytes
Different tools exist to process the information
Flowtools, flowc
NFSen
Many more: http://www.networkuptime.com/tools/netflow/
Statistics and accounting tools
36. Is the problem transient?
Overload, temporary resource shortage
Is the problem permanent?
Equipment failure, link down
How do you detect an error?
Monitoring!
Customer complaints
A ticket system is essential
Open ticket to track an event (planned or failure)
Define dispatch/escalation rules
Who handles the problem?
Who gets it next if no one is available?
Fault and problem management
37. Why are they important?
Track all events, failures and issues
Focal point for helpdesk communication
Use it to track all communications
Both internal and external
Events originating from the outside:
customer complaints
Events originating from the inside:
System outages (direct or indirect)
Planned maintenances or upgrades – Remember to
notify your customers!
Ticketing systems
38. Use ticket system to follow each case,
including internal communication between
technicians
Each case is assigned a case number
Each case goes through a similar life cycle:
New
Open
...
Resolved
Closed
Ticketing systems
39. Workflow:
Ticket System Helpdesk Tech Eqpt
----------------------------------------------------------------
T T T T
query | | | |
from ---->| | | |
customer |--- request --->| | |
<- ack. -- | | | |
| |<-- comm --> | |
| | |- fix issue -> eqpt
| |<- report fix -| |
customer <-|<-- respond ----| | |
| | | |
Ticketing systems
40. rt (request tracker)
Heavily used worldwide.
A classic ticketing system that can be customized to
your location.
Somewhat difficult to install and configure.
Handles large-scale operations.
trac
A hybrid system that includes a wiki and project
management features.
Ticketing system is not as robust as rt, but works well.
Often used for ”trac”king group projects.
redmine
Like trac, but more robust. Harder to install
Ticketing systems: examples
41. These are systems that observe all of your network
traffic and report when it sees specific kinds of
problems, such as:
hosts that are infected or are acting as spamming sources.
A few tools:
SNORT - a commonly used open source tool:
http://www.snort.org/
Prelude – Security Information Management System
https://dev.prelude-technologies.com/
Samhain – Centralized HIDS
http://la-samhna.de/samhain/
Nessus - scan for vulnerabilities:
http://www.nessus.org/download/
Network Intrusion Detection
Systems (NIDS)
42. Record changes to equipment configuration using
revision control (also for configuration files)
Inventory management (equipment, IPs,
interfaces)
Use versioning control
As simple as:
”cp named.conf named.conf.20070827-01”
For plain configuration files:
CVS, Subversion (SVN)
Mercurial
• For routers:
- RANCID
Configuration mgmt & monitoring
43. Traditionally, used for source code (programs)
Works well for any text-based configuration files
Also for binary files, but less easy to see differences
For network equipment:
RANCID (Automatic Cisco configuration retrieval and
archiving, also for other equipment types)
Built-in to Project Management Software like:
Trac
Redmine
And, many other wiki products. Excellent for
documenting your network.
Configuration mgmt & monitoring
44. - Monitoring
- Data collection
- Accounting
- Capacity planning
- Availability (SLAs)
- Trends
- Detect problems
- Change control &
monitoring
- Improvements
- Upgrades
- Fix problems
- User complaints
- Requests
- NOC Tools
- Ticket system
Ticket
Ticket
Ticket
Ticket
Ticket
Notifications
The big picture revisited
